An optical fiber comprises a core of high index material surrounded by a cladding of low index material. The diameter of the core ranges from about 9 .mu.m for single mode transmission to about 62 .mu.m for multimode transmission. The external diameter of the cladding is generally about 125 .mu.m or 140 .mu.m, regardless of the diameter of the core. The fiber is provided with a plastic buffer coating to protect it from damage.
Although optical fibers can, using known technology, be manufactured so as to have essentially uniform properties over essentially indefinite lengths, it is conventional for such fibers to be sold in lengths of, e.g., one km, and for two or more lengths of fiber to be spliced together, i.e. joined together end-to-end, in order to produce a fiber longer than one km. Moreover, even though a fiber of one km or more can readily be manufactured so that it is without significant defects, handling of the fiber during installation as part of a fiber optic link may result in damage to the fiber, rendering it necessary to remove the damaged portion of the fiber and splice the undamaged portions together. Accordingly, techniques for splicing optical fibers have been developed. Several techniques that are currently in use in installation of fiber optic links involve use of special splice units for receiving the ends of the fibers to be spliced and holding those ends in accurately-determined alignment. It will be understood that any error in alignment of the ends of the fibers results in potential loss in transmission of optical energy through the splice. The splice units are, therefore, manufactured to high accuracy and they typically include several components. Consequently, such units are expensive. The splice units themselves remain permanently installed on the spliced fiber, and therefore cannot be used in making multiple splices.